I recently read, in a book, that veterinarians still aren't certain about why dogs will consume other dog's feces. However, the book is several years old now. I've also read these theories online: ~ The dog is not getting enough nutrition in their food. ~ A mother dog will eat her puppies' feces to keep the den area clean, and some of them will keep the habit after watching her. ~ A younger, healthier dog wants to remove "evidence" of an older/sick dog being in poor health.